Horizontal re-pulping apparatus for cellulose fibres

ABSTRACT

A pulping apparatus includes a hollow mixing cylinder selected to retain a volume of pulping fluid and cellulose fibres therein. The mixing cylinder is journaled for rotation about a central axis oriented at approximately +20° from horizontal. In a preferred construction, the mixing cylinder is divided internally into at least two discrete mixing chambers configured to facilitate outward flow of defibred pulp from an infeed end of the cylinder to and outwardly from the outlet end. The mixing chamber adjacent the inlet end is delineated by an end cover which closes the inlet end, and by a first divider positioned across the cylinder interior. The next adjacent mixing chamber is delineated longitudinally by the distal-most divider of the end mixing chamber, and by a second further downstream divider spaced longitudinally therefrom. The dividers include at least one through-opening therethrough. The through-openings regulate the flow of pulp and fluid along the mixing cylinder, while maintaining minimum cellulose/fluid levels in each mixing chamber. The through-openings may be positioned in alignment with, or in an asymmetrical arrangement relative to the cylinder axis so as to move eccentrically relative thereto as the mixing cylinder rotates.

SCOPE OF THE INVENTION

The present invention relates to an apparatus for use in the pulping ofcellulose fibres, and more preferably a pulping apparatus for use in thepulping or re-pulping and hydration of virgin cellulose or recycledpaper and cardboard fibres.

BACKGROUND OF THE INVENTION

The use of pulpers in paper manufacturing processes to form virgin orrecycled pulp is well known. Conventionally, pulpers are constructedwith large vertically elongated mixing tanks or vats in which rawcellulose material, water and pulping chemicals are mixed. The vatstypically have a diameter of between about 3 and 5 metres and may exceed3 metres in height. A large rotor or mixing blade positioned at thebottom of the vat is used to break up the cellulose material into smallfibres in the formation of pulp. In operation, bales of virgin orrecycled cellulose such as paper or cardboard, are fed into the vat andmixed with the water/chemical pulping fluid by the agitation of themoving rotor, to defibre and pulp the mixture for further use.

Conventional pulpers and re-pulpers (hereinafter generally referred toas pulping apparatus) suffer a disadvantage in that because of the largesize and vertical orientation of the pulping vat, high horsepowerelectric motors of 500 horsepower or more, are required to drive themixing rotor. The use of high horsepower motors dramatically increasesenergy use and the operation in costs of entire system. As a result, theuse of conventional pulpers is frequently cost prohibitive in re-pulpingrecycled cellulose fibres such as paper and cardboard waste.

Another disadvantage exists with conventional pulpers in that as themixing rotors are often constructed in a form of an oversized agitatormounted to the bottom floor of the mixing vat with a diameter and/orheight of up to two metres. In addition to the requirement to provideadequate rotary seals, the drive assemblies used to couple the rotors tothe motor require complex and expensive gearing and transmissions whichare susceptible to fatigue and failure.

Conventional pulping apparatus suffer a further disadvantage in that ifthe mixing rotor or blade is damaged, it is necessary to firstcompletely drain and empty the mixing vat to permit maintenance accessto the damaged blade. This may involve the added expense andinconvenience of having to manually remove any unpulped cellulosethrough the bottom of the vat.

SUMMARY OF THE INVENTION

To at least partially overcome at least some of the difficultiesassociated with prior art devices, the present invention provides for apulping apparatus which includes a hollow mixing cylinder which isjournaled for rotation about a generally horizontal cylinder axis. Themixing cylinder includes a generally solid sidewall which extendsradially about the central axis from a proximal inlet end to an outletend distal therefrom. The interior of the mixing cylinder is dividedinto two or more discrete chambers which are configured to break-upand/or hydrate input cellulose fibres to form a desired pulp as thecylinder rotates. A drive is provided to rotate the mixing cylinderabout its central axis, while cellulose and pulping fluid is fedtherein.

Accordingly, one object of the present invention is to provide a pulperor re-pulper which may be operated more cost effectively using a drivewhich includes a low horsepower motor having a horsepower less thanabout 100 bhp, preferably less than about 50 bhp, and most preferablybetween about 20 and 30 bhp.

Another object of the invention is to provide a pulping apparatus foruse in the hydration and pulping of either virgin, or more preferablyrecycled cellulose fibres, and which is provided with one or morehorizontally extending cylindrical mixing chambers adapted for rotationabout a generally horizontal (±20°) axis, as part of a substantiallycontinuous pulping operation.

Another object of the invention is to provide a pulping apparatus whichis adapted to permit the rapid and simplified replacement and/or repairof damaged pulper mixing blades or vanes, without requiring the completeemptying of mixing tank or chamber.

A further object of the invention is to provide a pulping apparatuswhich is adapted for use as part of a continuous production line, andwhich provides the enhanced defibring of recycled paper and cardboardmaterials, while minimizing fibre damage.

Yet another object of the invention is to provide a pulping apparatuswhich incorporates a horizontally elongated mixing cylinder which isrotatable about a central cylinder axis by way of a conventional directchain drive, without the requirement of complex gearing and/ortransmission assemblies.

To at least partially achieve at least some of the foregoing objects,the present invention provides for a pulping apparatus which includes ahollow mixing cylinder, a drive assembly, and a feed hopper assemblyoperable to supply cellulose material to an interior of the cylinder.The mixing cylinder has size selected to receive and retain therein aselected volume of pulping fluid and cellulose fibres. The mixingcylinder includes a cylinder sidewall which extends radially about acentral cylinder axis, a proximal inlet end to an outlet end spaced in alongitudinal direction distally therefrom. The mixing cylinder isjournaled for rotation about its central axis, with the axis oriented at±20° from horizontal, preferably ±10°, and most preferably at about ±3°from horizontal.

The drive assembly includes a motor selectively actuable to rotate themixing cylinder during pulping operations. Preferably, the motor is alow horsepower electric motor having a horsepower of less than about 100hp, preferably less than about 50 hp, and most preferably between 20 and30 hp. Other types and sizes of motors may however, also be used. Thefeed hopper assembly is adapted for supplying virgin or recycledcellulose fibres and preferably pulping fluid into an inlet end portionof the mixing cylinder, as part of either a batch or continuous process.

In a preferred construction, the mixing cylinder is provided with asolid cylinder sidewall and is divided internally into at least two, andpreferably three or more discrete mixing chambers. The mixing chambersare each configured to maintain a minimum pulp/fluid level therein,while facilitating the outward flow of defibred pulp from the cylinderinfeed end to and outwardly from the outlet end. The first mixingchamber is characterized by a series of mixing and cutting vanes,blades, flutes, or plow bars (hereinafter generally referred to ascutting blades) mounted to the interior cylindrical wall of the mixingchamber. The cutting blades are configured to facilitate the mixing,breakdown and defibring of the cellulose material in the pulping fluidas the mixing cylinder is rotated about its central axis. The firstmixing chamber is delineated longitudinally at a proximal most first endby an end cover or sealing member, and at its second distalmost end, bya first divider provided laterally across the interior of the cylinder adistance spaced distally from the end cover. The end cover is configuredto substantially close the inlet end of the cylinder to prevent thereverse flow of pulping fluid and/or cellulose therefrom. In onesimplified construction, the hopper assembly includes a feed pipeconfigured to convey cellulose fibres and/or pulping fluid through aninlet opening formed in the end cover and into the mixing cylinderinterior.

The next immediately adjacent downstream mixing chamber is delineatedlongitudinally by the distalmost first divider of the first mixingchamber, and by a second further downstream divider extending across thecylinder interior spaced longitudinally therefrom. The second mixingchamber may furthermore include cutting vanes or blades or internalribs, but most preferably is characterized by a generally smooth chambersidewall.

Each of the dividers are provided with one or more flow passages orthrough-openings formed therethrough. The through-openings of eachdivider are configured to regulate the flow of pulp and any or partiallypulped material and pulping fluids longitudinally along the mixingcylinder and outwardly therefrom through the outlet end. The cylinderdividers preferably act as weirs to maintain minimum cellulose/fluidlevels in each mixing chamber as the cylinder is rotated. Preferably,the second divider is configured to maintain a minimum fluid level inthe second mixing chamber selected less than the minimum level of fluidmaintained in the first.

In a simplified construction, each through opening is formed as agenerally circular opening which is substantially centered on thecylinder axis. The diameter of the through-opening formed through thesecond divider is selected larger than the diameter of thethrough-opening which is formed in the first divider, maintaining alower minimum fluid level in the second mixing chamber. Optionally, theend cover may also be provided with a circular outlet opening having adiameter which is greater than that of the second through-opening tomaintain a minimum fluid level between the end cover and second dividerplate, which is lower than the level maintained between the first andsecond dividers.

In an alternate construction, all or part of the through-openings whichextend through the divider may be positioned in an asymmetricalarrangement relative to the central axis, so as to move eccentricallyrelative to the central axis as the mixing cylinder is rotated. Althoughnot essential, most preferably the flow through-passages are spaced fromthe cylinder sidewall to restrict the movement of larger fibre particlesfrom moving outwardly therefrom. More preferably, the eccentricallymoving portion of the flow through-openings formed through the seconddownstream divider has a greater total area than the eccentricallymoving portion of the flow through-openings formed through the firstdivider, with the maximum fluid/pulp flow from the first mixing chamberbeing less than that from the second chamber. Further as the mixingcylinder rotates, the eccentric rotation of the through-openingsprovides for the variable fluid flow past each divider during use of theapparatus.

As such, with the present invention after an initial period of residencetime in the first mixing chamber, fluid and pulp will thereafter tend toflow into and be retained in the second mixing chamber for a period oftime, prior to flowing outwardly therefrom.

Accordingly, in one aspect the present invention resides in a pulpingapparatus for the hydration of recycled cellulose fibres comprising ahollow mixing cylinder having a cylinder wall which extends radiallyabout a central axis oriented at approximately ±10° from horizontal, thecylinder being mounted for rotation about the axis and extendinglongitudinally therealong from a proximal inlet end to a distal outletend, and including an end cover partially closing said inlet end, theend cover including an inlet opening spaced inwardly from said cylinderwall towards said axis; a first divider extending laterally across aninterior of said cylinder, the first divider being distally spaced fromsaid end cover to define a first mixing chamber therebetween, a firstflow passage formed through said first divider, the first flow passagehaving a first diameter; a second divider extending laterally across aninterior of the cylinder, the second divider being distally spaced fromthe first divider plate to define a second mixing chamber therebetween,a second flow passage formed through said second divider; a hopperassembly for conveying said cellulose fibres into said cylinder throughsaid inlet opening; a drive assembly selectively actuable to rotate saidcylinder about said axis.

In another aspect, the present invention resides in a pulping apparatusfor cellulose fibres comprising a hollow mixing cylinder having acylinder wall which extends radially about a central axis oriented atapproximately ±10° from horizontal, the cylinder being journaled forrotation about the axis and extending longitudinally therealong from aproximal inlet end to a distal outlet end; an end cover partiallyclosing said inlet end and including an inlet opening; an infeed hopperassembly for conveying said cellulose fibres into said cylinder throughsaid inlet opening; a fluid supply for supplying a pulping fluid intosaid cylinder for admixture with said cellulose fibres; a first dividerplate disposed in said cylinder, the first divider plate beinglongitudinally spaced from said end cover to define a first mixingchamber therebetween, a first flow passage formed through said firstdivider plate, the first flow passage configured to maintain a firstminimum fluid level in the first mixing chamber as said cylinder isrotated about said axis; a second divider plate disposed in saidcylinder, the second divider plate being remote from said end cover andlongitudinally spaced from said first divider plate to define a secondmixing chamber therebetween, a second flow passage formed through saidsecond divider plate, the second flow passage configured to maintain asecond minimum fluid level in the second mixing chamber as said cylinderis rotated about said axis, the second fluid level being less than thefirst fluid level; a drive assembly selectively actuable to rotate saidcylinder about said axis.

In a further aspect, the present invention resides in a hollow mixingcylinder having a generally solid cylinder wall which extends radiallyabout a central axis oriented at approximately ±3° from horizontal, thecylinder being mounted for rotation about the axis and extendinglongitudinally therealong from a proximal inlet end to a distal outletend and including; an end cover partially closing said inlet end, theend cover including an inlet opening; a first divider disposed in saidcylinder, the first divider being distally spaced from said end coverand generally sealing with said cylinder wall to define a first mixingchamber therebetween, a first flow passage formed through said firstdivider, the first flow passage having a first diameter; a seconddivider being disposed in the cylinder, the second divider beingdistally spaced from the first divider and sealing with said cylinderwall to define a second mixing chamber therebetween, a second flowpassage formed through said second divider; an end cover distally spacedfrom the second divider and defining a third mixing chambertherebetween, an outlet flow opening formed through said end cover, theoutlet flow opening having a third diameter selected greater than thesecond diameter; an infeed hopper assembly for conveying a slurry ofsaid recycled paper and cardboard fibres and a fluid into said cylinderthrough said inlet opening; a drive assembly selectively actuable torotate said cylinder about said axis.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference may now be had to the following detailed description, takentogether with the accompanying drawings in which:

FIG. 1 shows a perspective view of a pulping apparatus in accordancewith a preferred embodiment of the invention;

FIG. 2 shows a partially cut away side view of the apparatus shown inFIG. 1, illustrating the positioning of cutting blades in a first mixingchamber;

FIG. 3 shows a cut away perspective view of the pulping apparatus ofFIG. 1, showing the positioning of longitudinally spaced mixing chamberswithin the mixing cylinder;

FIG. 4 shows a cross-sectional view of the pulping cylinder shown inFIG. 2 taken along line 4-4, illustrating the relative positioning ofdivider flow through-openings relative to the cylinder axis, inaccordance with a first embodiment of the invention;

FIG. 5 shows a cross-sectional view of the pulping cylinder as shown inFIG. 5, illustrating the positioning of the divider flowthrough-openings in maintaining minimum pulp/fluid levels in thecylinder mixing chambers;

FIG. 6 shows a cross-sectional view of the pulping cylinder shown inFIG. 2 taken along line 4-4 illustrating the relative positioning ofdivider flow through openings relative to the cylinder axis, inaccordance with a second embodiment of the invention; and

FIG. 7 shows a cross-sectional view of the pulping cylinder showing therelative positioning of the divider flow through-openings in accordancewith a further embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference is first made to FIG. 1 which shows best a pulping apparatus10 for use in the re-pulping of recycled cardboard and paper waste inaccordance with a preferred embodiment of the invention. The pulpingapparatus 10 includes a mixing cylinder 12, a drive assembly 14 and ahopper assembly 16 which are mounted on a support frame 18. As welldescribed, the hopper assembly 16 is used to supply a slurry mixture 8(FIG. 2) of pulping fluid and recycled paper and cardboard fibres intothe interior of the mixing cylinder 12 for re-pulping and formation of acleared pulp 8″, which for example, is suitable for use in subsequentpaper processing applications.

The mixing cylinder 12 is shown best in FIGS. 2 and 3 as having agenerally solid stainless steel sidewall 22 which extends radially abouta central cylinder axis A₁-A₁. As shown best in FIG. 2, the mixingcylinder sidewall 22 is rotatably supported towards each end of thecylinder 22 by opposing pairs of roller wheels 28 a, 28 b which aresecured to the support frame 18. The cylinder 12 is extendslongitudinally along the axis A₁-A₁, from an inlet end 24 which ispositioned proximal-most to the hopper assembly 16, to an outlet end 26spaced distally therefrom. As will be described, the mixing cylinder 12is positioned on the rollers 28 a, 28 b with the axis A₁-A₁ in agenerally horizontal orientation (±3°), so as to be selectivelyrotatable thereabout by the activation of the drive assembly 14.

In a preferred construction, the mixing cylinder 12 is provided with anoverall longitudinal length selected at between about 3 and 6 metres,and a lateral diameter of between about 1 and 3 metres, and mostpreferably about 2 metres. Mixing cylinders 12 having larger or smallerdiameters and/or lengths may however, also be used depending on the typeand volume of material to be pulped.

FIG. 3 shows best the mixing cylinder 12 as being divided internallyinto three separate mixing chambers 30, 32, 34 which are each delineatedradially by the cylinder sidewall 22. The first proximal-most mixingchamber 30 adjacent to the inlet end 24, is delineated in a longitudinaldirection by a cylinder end cover 36 at a proximal end, and by a firstdivider plate 38 at a downstream end 1.5 to 2.5 metres distal therefrom.The end cover 36 is preferably formed as a stainless steel plate whichis bolted or welded over the inlet end 24 of the cylinder 12 tosubstantially prevent the outflow of the pulping fluid/cellulose fibreslurry mixture 8 outwardly therepast. An axially aligned circular endopening 40 is formed through the end cover 36. As will be described, theend opening 40 is configured for cooperation with an infeed pipe 76 ofthe hopper assembly 16, to permit the substantially continuous inputflow of the raw slurry mixture 8 therethrough, and into the mixingchamber 30 during pulping operations.

The downstream divider plate 38 is formed as a circular stainless steelplate which extends laterally across the interior of the mixing cylinder12 in an orientation substantially transverse to the axis A₁-A₁.Although not essential, most preferably the divider plate 38 is mountedin a substantially sealing arrangement with the cylinder sidewall 22, toprevent the movement of cellulose fibres and/or pulp therebetween.

As shown best in FIGS. 2 and 3, a number of longitudinally spacedcutting blades or vanes 40 a, 40 b, are fixedly secured to the cylindersidewall 22, radially about the mixing chamber 30. The cutting vanes 40a, 40 b are shown as being formed as rigid curved bars, and have alength and configuration selected to facilitate the defibering andbreakdown of the raw cellulose material 8 as it moves therethrough inthe chamber 30, as the mixing cylinder 12 is rotated. Other cutting vaneconfigurations are however, possible.

FIGS. 3 and 4 illustrate best the divider plate 38 as having athrough-opening 42 formed therethrough. Although not essential, mostpreferably the through-opening 42 is formed as a circular opening havinga diameter d₁ selected at between about 20 and 50 cm. Thethrough-opening 42 is furthermore formed through the divider plate in anasymmetrical position relative to the central axis A₁-A₁, whereby theradial centre C₁ (FIG. 4) of the through-opening 42 is offset from theaxis A₁-A₁ by a distance of between about 10 and 25 cm. It is to beappreciated that with this configuration, the rotation of the mixingcylinder 12 about the central axis A₁-A₁ in the direction of arrows 100(FIG. 5), moves the through-opening 42 eccentrically relative to thecylinder axis A₁-A₁.

FIG. 3 shows best the second mixing chamber 32 as immediately adjacentto and downstream from the chamber 30. The mixing chamber 32 has asubstantially smooth radial surface, and is delineated in thelongitudinal direction by the first divider plate 38 at its proximalend, and at its second distalmost end by a second divider plate 48. Mostpreferably, the second divider plate 48 is spaced a distance of betweenabout 1.5 and 2.5 metres from the divider plate 38. The divider plate 48is provided in a substantially sealing arrangement with the sidewall 22and includes a generally circular through-opening 52 formedtherethrough.

As shown best in FIG. 4, the through-opening 52 is provided with adiameter d₂ which is selected greater than the diameter d₁, and whichpreferably is selected at between about 30 and 60 cm. The radial centreC₂ of the through-opening 52 is laterally offset from the axis A₁-A₁ toprovide for the eccentric movement of the through-opening 52 relativethereto, as the mixing cylinder 12 is rotated. Although not essential,preferably centre C₂ of the through-opening 52 is spaced from the axisA₁-A₁ a greater distance, and in the same radial direction as the centreC₁ of through-opening 42.

The downstream-most mixing chamber 34 is likewise provided with agenerally smooth sidewall and is delineated longitudinally by the seconddivider plate 48 at its proximalmost inner end, and an outlet cap plate54 at its distalmost outer end. The cap plate 54 is formed provided as astainless steel plate 54 which partially closes the distal end of themixing cylinder 12. An outlet flow passage or opening 62 formed throughthe cap plate 54 permits the outflow of the re-pulped fibres 8″ from themixing cylinder 12 for further processing and/or manufacturingapplications. The outflow opening 62 is likewise provided for eccentricmovement relative to the axis A₁-A₁. In this regard, the opening 62 isformed as a circular opening having a diameter d₃ (FIG. 4) which isselected larger than the diameter d₂ of the through-opening 52. Mostpreferably, the diameter d₃ is selected at between about 80 and 120 cm,and most preferably about 100 cm. The centre C₃ of the outlet flowopening 62 is shown best in FIG. 4 as being spaced radially from theaxis A₁-A₁, in substantially the same direction as centres C₁ and C₂,and preferably, with the centre C₃ is located radially outwardly fromthe centre C₂ of through-opening 52.

Although not essential, in a most preferred construction the minimumradial distances between each of the openings 42, 52 and 62 and the axisA₁-A₁ are approximately equal. The eccentric movement of the openings42, 52 and 62 relative to the axis A₁-A₁, results in the cross-sectionalarea of the through-opening 52 which is moved eccentrically beinggreater than the area eccentrically moved portion of the through-opening42. Similarly, the portion of the outlet flow opening 62 which moveseccentrically about the axis A₁-A₁, has a greater cross-sectional areathan the eccentrically moved portion of the second through-opening 52.As such, as the cylinder 12 rotates, the first divider plate 38 acts asa weir to maintain a greater minimum level L₁ of raw slurry 8 in thefirst mixing chamber 30. This increases the residence time of the slurry8 in the end chamber 30, allowing for maximum mechanical defibration bythe rotating cutting vanes 40 a, 40 b. Because of its larger diameter,d₂ a greater area of the through-opening 52 moves eccentrically relativeto the axis A₁-A₁, than that of the first flow passage 42. As a result,the through-opening 52 results in a greater outward flow of slurry 8′from the chamber 32 than that from the mixing chamber 30. The dividerplate 48 thus maintains a lower minimum level L₂ of pre-treated slurry8′ in the chamber 32 less than the level L₁. This ensures the downstreamfluid flow from the first mixing chamber 30, into the second mixingchamber 32 when the opening centres C₁, C₂ are moved downwardly directlybelow (±120°) the axis A₁-A₁.

Similarly, the larger diameter d₃ of the outlet flow opening 62 allowsfor a greater outward flow of treated pulp 8″ therethrough, then flowsthrough the through-opening 52. This results in the end cover plate 54maintaining a minimum fluid/slurry 8″ mixture level L₃ in the mixingchamber 34 which is less than the level L₂. This again ensures thecontinued downstream flow of pulp 8″ from chamber 32 into and then fromchamber 34.

In this configuration, the slurry 8′ flows along the mixing cylinder 12sequentially from the first mixing chamber 30, to the second mixingchamber 32, and thereafter from the second mixing chamber 32 into thethird mixing chamber 34, prior to moving outwardly therefrom via theoutlet flow opening 62. The eccentric positioning of thethrough-openings 42, 52 and outlet flow opening 62 further provide avariable slurry 8 flow therethrough. Most preferably, the openings 42,52 and 62 are provided to restrict or substantially prevent fluid flowfrom the mixing chambers 30, 32, 34, respectively as the mixing cylinder12 is rotated through between about 70° and 120° of movement when forexample the centres C₁, C₂, C₃ are moved to a position above the axisA₁-A₁. The variable flow advantageously eliminates the formation laminarflow across the top of the slurry volume 8, 8′ and 8″ in each chamber30, 32, 34, respectively. In addition, variable flow increases theresidence time of the pulp fibres in each of the mixing chambers 30, 32,34, to maximize the time period for rehydration, agitation andmechanical working by the cutting vanes 40.

FIGS. 1 and 2 show best the drive assembly 14 as including an electricmotor 64 which is coupled in a direct drive manner to a drive chain 66.Optionally a shroud box 70 (FIG. 1) may be secured in place over thechain drive 66 and output motor shaft 64 for enhanced safety. The drivechain 66 frictionally engages a rack 68 formed on the end cover 36 andwhich extends radially about the axis A₁-A₁. The applicant hasappreciated that by coupling the motor 64 to the cylinder 12 directly byway of a simple drive chain 66 allows for the use of low horsepowermotors. In particular, motors having horsepower selected at less thanabout 50 hp, and preferably about 20 to 30 hp may be used to drive thecylinder 12 in rotation about the axis A₁-A₁. This constructionadvantageously enables the more economical operation of the pulpingapparatus 10, lowering operational costs and thereby increasing theoperational efficiency of the apparatus 10 as contrasted withconventional pulpers.

FIG. 3 shows best the hopper assembly 16 as including a hopper box 74,infeed pipe 76 and pulping fluid conduits 78. The hopper box 74 opensalong its lower most centre into an upper most portion of the feed pipe76. The feed pipe 76 extends in a generally downwardly slopingconfiguration through the end cover opening 40 to provide fluidcommunication with the first mixing chamber 30. Most preferably, anelectric feed auger 80 is disposed within the feed pipe 76. The auger 80is operable to assist in the movement of the fluid cellulosefibre/slurry 8 from the hopper box 74 and into and along the feed pipe76 and into the cylinder 12.

It is to be appreciated that fluid conduit pipes 78 provide fluidcommunication between a water and pulping chemical sources (not shown)and an upper portion of the hopper box 74. The conduit pipes 78 mostpreferably supply water and pulping fluid into the upper portion ofhopper box 74 to assist in the flow of slurry 8 into mixing cylinder 12via the feed pipe 76. It is to be appreciated that other constructionsfor supplying pulping fluid into the cylinder 12 may also be used.

In use of the apparatus of FIG. 1, the electric motor 64 is initiallyactuated to rotate the mixing cylinder 12 about the axis A₁-A₁.Partially shredded recycled paper and cardboard cellulose fibres are fedin a continuous manner into the open hopper box 74. Concurrently, waterand pulping fluid is supplied to the hopper box 74 via the conduit pipes78, with the electric feed auger 80 is activated to provide asubstantially constant supply of the raw slurry 8 into the first mixingchamber 30.

As the input raw slurry 8 moves into the first mixing chamber 30, therotation of the cylinder wall 22 moves the cutting vanes 40 through theslurry 8 to assist in breaking up the cellulose fibres a first stageprocess. Because of the smaller diameter d₁ and eccentric movement ofthe through-opening 42, as the mixing cylinder 12 rotates, the partiallyprocessed slurry 8 mixture will move from the first mixing chamber 30,through the divider plate 38 and into the second mixing chamber 32 at avariable rate, with an increased flow occurring as the through-opening42 travels along a downwardly extending arc, and with a reduced flowrate as to the centre of the opening 42 moves upwardly relative to theaxis A₁-A₁.

As the partially processed slurry 8′ moves into the second mixingchamber 32, the smooth sidewall of the second mixing chamber results inthe settling of heavier unhydrated cellulose fibres towards the chamberbottom 12. As the residence time of the heavier cellulose fibresincreases, the fibres tend to more fully hydrate. The rotation of themixing cylinder 12 in turn results in the buoyancy of the more hydratedcellulose fibres towards the top portion of the slurry 8′. The hydratedfibres tend to move by way of variable flow through the opening 52 andinto the third mixing chamber 34, as the flow volume from the mixingchamber 32 increases with the eccentric movement of the through-opening52 along the downwardmost path of movement.

In the third mixing chamber 34, any remaining heavier unhydrated orpartially hydrated fibres 8″ tend to settle towards the bottom of thechamber 34. The partially hydrated fibres thus are similarly retained inthe mixing chamber 34 resulting in more complete hydration, prior tomovement through outlet flow passage 62, the eccentric path of theopening 62 providing variable flow therefrom.

Although the preferred embodiment shown in FIG. 3 illustrates the mixingcylinder 12 as including a number of cutting vanes 40 within the mixingchamber 30, the invention is not so limited. It is to be appreciatedthat in an alternate construction, cutting or mixing blades, vanes,ploughs or other equivalent structures could be included in one or moreof each of the mixing chambers 30, 32, 34, without departing the spiritand scope of the invention.

While FIG. 3 shows the cylinder 12 as having three separate mixingchambers 30, 32, 34, it is to be appreciated that in an alternateconfiguration, the mixing cylinder 12 could include either additional orfewer mixing chambers without departing from the spirit and scope of theinvention.

Although FIG. 4 illustrates the centres C₁, C₂, C₃ of thethrough-openings 42, 52 and outlet flow opening 62 as being spacedradially in the same direction away from the axis A₁-A₁, the inventionis not so limited.

FIG. 6 illustrates an alternate possible through-opening configuration,wherein like reference numerals are used to identify like components. InFIG. 6, each of the through-openings 42, 52, 62, is formed as acylindrical opening which are arranged in a concentric position centeredon the axis A₁-A₁. Through-opening 42 is provided with a diameter d₁which is preferably selected at between about 30 and 60 cm.Through-opening 52, is provided with a diameter d₂ which is greater thanthe diameter d₁, and most preferably which is selected at between about50 and 100 cm. The outlet flow opening 62 is formed with a diameter d₃,which is selected greater than d₂, and is preferably sized between about100 and 150 cm. It is to be appreciated that larger or smaller diameteropenings 42, 52, 62 could equally be provided.

From the construction shown, it is to be appreciated that the smallerdiameter of the through-opening 42 acts as a weir to maintain a higherlevel L₁ of pulp 8 in the mixing chamber 30, than the level L₂maintained in mixing chamber 32. Similarly, because of the largerdiameter d₃ of the outlet opening 62, the level of pulp 8″ (FIG. 2) ismaintained in the mixing chamber 34 at a lower level L₃ which is lessthan the level L₂.

The greater volume of fluids maintained in the mixing chamber 30 acts toincrease the residence time of the pulp therein as the cylinder 12rotates about the axis A₁-A₁.

FIG. 7 illustrates yet a further alternate possible through-openingconfiguration, wherein like reference numerals are used to identify likecomponents. In the construction shown in FIG. 7, the through-opening 52of the second divider plate 48 is positioned for eccentric movement in aradially opposite manner as the path of movement for the through-opening42, and outlet flow passage 62. It is to be appreciated that theconstruction of FIG. 7 advantageously allows for the backflow of slurry8 within the cylinder 12 as it rotates. Other opening positions and/orconfigurations are also possible and will now become apparent.

Similarly, although FIGS. 4, 6 and 7 illustrate the through-openings 42,52 and outlet flow opening 62 as each having axially overlappingcircular shapes, the invention is not so limited. It is to beappreciated that the through-openings could be provided a variety ofshapes, including without restriction, either a polygonal ornon-geometric profile. Alternately, the divider plates 38, 48 and/or endcap plate 54 could be provided with multiple openings as fluid flowpassages adapted to permit variable fluid flow therethrough, whilemaintaining the desired minimum fluid levels in each of the mixingchambers 30, 32, 34.

Although FIG. 3 illustrates the second and third mixing chambers 32, 34as having a substantially smooth solid radial sidewall, the invention isnot so limited. If desired, the mixing chambers 32, 34 could equallyinclude vanes, mixing members, or agitators without departing from thespirit and scope of the invention.

Although the detailed description describes and illustrates the pulpingapparatus 10 as being used in the re-pulping of waste cardboard andpaper, the invention is not so limited. In an alternate use, theapparatus is equally suitable for use as a pulper in the processing anddefibration of virgin cellulose material.

While the detailed description describes the pulping apparatus 10 asincorporating a low voltage electric motor 64 and drive chain 66, theinvention is not so limited. It is to be appreciated that in a lesspreferred construction, higher horsepower motors and/or geared drivelinkages and/or transmission could alternately be employed to effectrotational movement of the mixing cylinder 12, without departing fromthe spirit and scope of the invention.

Although the detailed description describes and illustrates as preferredaspects, the invention is not so limited. Many modifications andvariations will now occur to persons skilled in the art. For adefinition of the invention, reference may be had to the appendedclaims.

1. A pulping apparatus for the hydration of recycled cellulose fibrescomprising: a hollow mixing cylinder having a cylinder wall whichextends radially about a central axis oriented at approximately ±10°from horizontal, the cylinder being mounted for rotation about the axisand extending longitudinally therealong from a proximal inlet end to adistal outlet end, and including an end cover partially closing saidinlet end, the end cover including an inlet opening spaced inwardly fromsaid cylinder wall towards said axis; a first divider extendinglaterally across an interior of said cylinder, the first divider beingdistally spaced from said end cover to define a first mixing chambertherebetween, a first flow passage formed through said first divider,the first flow passage having a first diameter; a second dividerextending laterally across an interior of the cylinder, the seconddivider being distally spaced from the first divider plate to define asecond mixing chamber therebetween, a second flow passage formed throughsaid second divider; a hopper assembly for conveying said cellulosefibres into said cylinder through said inlet opening; a drive assemblyselectively actuable to rotate said cylinder about said axis.
 2. Theapparatus as claimed in claim 1 wherein each of the first flow passageand the second flow passage comprises a generally circular openingpositioned in substantial alignment with the axis; the second flowpassage having a diameter selected greater than the first diameter. 3.The apparatus as claimed in claim 1 wherein the first flow passage isasymmetrically positioned relative to said axis, whereby rotation of thecylinder moves at least part of the first flow passage eccentricallyrelative to the axis; the second flow passage being asymmetricallypositioned relative to said axis, whereby rotation of the cylinder movesa part of the second flow passage eccentrically relative to the axis,and wherein the part of the second flow passage moved eccentrically hasa greater area than the part of the first flow passage movedeccentrically;
 4. The apparatus of claim 1 further including a fluidsupply, for supplying a hydrating fluid into the interior of thecylinder; the first fluid flow passage permitting variable fluid flowtherethrough and maintaining a first fluid level in the first mixingchamber as the cylinder is rotated, the second fluid flow passagepermitting variable fluid flow therethrough and maintaining a secondfluid level in the second mixing chamber as the cylinder is rotated, thesecond fluid level being less than the first fluid level.
 5. Theapparatus as claimed in claim 3, wherein the first and second dividerseach comprise metal plates, the first fluid flow passage comprises afirst circular opening having a diameter selected at between about 0.3and 0.7 metres and having a centre offset a first radial distance fromthe axis, and the second fluid flow passage comprises a second circularopening having a diameter selected at between about 0.5 and 1.2 metresand having a centre offset a second radial distance from the axis,greater than the first distance.
 6. The apparatus as claimed in claim 3,further including a cap plate partially closing the outlet end, the capplate spaced distally from the second divider and defining a thirdmixing chamber therebetween, an outlet flow passage formed through saidcap plate, the outlet flow passage being asymmetrically positionedrelative to the axis, whereby rotation of the cylinder moves a part ofthe outlet flow passage eccentrically relative to the axis, and wherethe part of the outlet flow passage moved eccentrically has a greaterarea than the part of the second flow passage moved eccentrically. 7.The apparatus as claimed in claim 1, wherein said cellulose fibrescomprise recycled cardboard and paper fibre. hopper assembly includes afeed auger operable to convey said recycled cardboard and paper fibresin a substantially continuous supply.
 8. The apparatus as claimed inclaim 3, wherein said cellulose fibres comprise recycled and cardboard.9. The apparatus as claimed in claim 1, wherein said drive assemblyincludes a low horsepower electric motor having a horsepower selectedless than about 50 bhp.
 10. The apparatus as claimed in claim 9, whereineach of the second mixing chamber and the third mixing chambers have asubstantially smooth solid sidewall.
 11. The apparatus as claimed inclaim 8, further including at least one vane member disposed in saidfirst mixing chamber, the at least one cutting blade member configuredto physically engage said cellulose and fibers and break-up saidrecycled paper and cardboard as the cylinder rotates about the axis. 12.A pulping apparatus for cellulose fibres comprising: a hollow mixingcylinder having a cylinder wall which extends radially about a centralaxis oriented at approximately ±10° from horizontal, the cylinder beingjournaled for rotation about the axis and extending longitudinallytherealong from a proximal inlet end to a distal outlet end; an endcover partially closing said inlet end and including an inlet opening;an infeed hopper assembly for conveying said cellulose fibres into saidcylinder through said inlet opening; a fluid supply for supplying apulping fluid into said cylinder for admixture with said cellulosefibres; a first divider plate disposed in said cylinder, the firstdivider plate being longitudinally spaced from said end cover to definea first mixing chamber therebetween, a first flow passage formed throughsaid first divider plate, the first flow passage configured to maintaina first minimum fluid level in the first mixing chamber as said cylinderis rotated about said axis; a second divider plate disposed in saidcylinder, the second divider plate being remote from said end cover andlongitudinally spaced from said first divider plate to define a secondmixing chamber therebetween, a second flow passage formed through saidsecond divider plate, the second flow passage configured to maintain asecond minimum fluid level in the second mixing chamber as said cylinderis rotated about said axis, the second fluid level being less than thefirst fluid level; a drive assembly selectively actuable to rotate saidcylinder about said axis.
 13. The apparatus as claimed in claim 12,wherein the first fluid flow passage comprises a first circular openinghaving a diameter selected at between about 0.3 and 0.7 metres; thesecond fluid flow passage comprises a second circular opening having adiameter selected at between about 0.5 and 1.2 metres.
 14. The apparatusas claimed in claim 12 wherein each of the first and second flowpassages having a centre which is offset from the axis to permit avariable fluid flow therethrough as the cylinder is rotated.
 15. Theapparatus as claimed in claim 14 wherein the centre of the second fluidflow passage is offset from the axis by a greater distance than that ofthe centre of the first fluid flow passage.
 16. The apparatus as claimedin claim 13, wherein the cylinder further includes a cap platelongitudinally spaced from the second divider plate and defining a thirdmixing chamber therebetween, an outlet flow opening formed through saidcap plate; the outlet flow opening positioned to provide a fluid flowtherethrough and maintain a third minimum fluid level in the thirdmixing chamber as the cylinder is rotated, the third fluid level beingless than the second fluid level.
 17. The apparatus as claimed in claim12, wherein said infeed hopper assembly includes a feed auger operableto convey recycled cardboard and paper waste into said cylinder as saidcellulose fibres in a substantially continuous supply.
 18. The apparatusas claimed in claim 13, wherein said drive assembly includes a lowhorsepower electric motor having a horsepower selected at between about20 and 35 bhp.
 19. The apparatus as claimed in claim 18, wherein saiddrive assembly further includes a chain drive for engagement with saidmixing cylinder.
 20. A pulping apparatus for the hydration of recycledpaper and cardboard fibres comprising: a hollow mixing cylinder having agenerally solid cylinder wall which extends radially about a centralaxis oriented at approximately ±3° from horizontal, the cylinder beingmounted for rotation about the axis and extending longitudinallytherealong from a proximal inlet end to a distal outlet end andincluding; an end cover partially closing said inlet end, the end coverincluding an inlet opening; a first divider disposed in said cylinder,the first divider being distally spaced from said end cover andgenerally sealing with said cylinder wall to define a first mixingchamber therebetween, a first flow passage formed through said firstdivider, the first flow passage having a first diameter; a seconddivider being disposed in the cylinder, the second divider beingdistally spaced from the first divider and sealing with said cylinderwall to define a second mixing chamber therebetween, a second flowpassage formed through said second divider; an end cover distally spacedfrom the second divider and defining a third mixing chambertherebetween, an outlet flow opening formed through said end cover, theoutlet flow opening having a third diameter selected greater than thesecond diameter; an infeed hopper assembly for conveying a slurry ofsaid recycled paper and cardboard fibres and a fluid into said cylinderthrough said inlet opening; a drive assembly selectively actuable torotate said cylinder about said axis.
 21. The apparatus as claimed inclaim 20 wherein each of the first flow passage and the second flowpassage comprise a generally circular opening positioned in generalco-axial alignment; the first flow passage maintaining a first fluidlevel in the first mixing chamber; the second flow passage maintaining asecond fluid level in the second mixing chamber less than the firstfluid level.
 22. The apparatus as claimed in claim 20 wherein the firstflow passage is non-aligned with said axis, whereby rotation of thecylinder moves the first flow passage eccentrically relative to theaxis; the second flow passage having a second diameter selected greaterthan the first diameter and being non-aligned with said axis, wherebyrotation of the cylinder moves the second flow passage eccentricallyrelative to the axis; and the outlet opening is non-aligned with saidaxis, whereby rotation of the cylinder moves the outlet flow openingeccentrically relative to the axis.
 23. The apparatus as claimed inclaim 21, wherein said infeed hopper assembly includes a feed augeroperable to convey said slurry into said first mixing chamber in asubstantially continuous supply.
 24. The apparatus as claimed in claim22, wherein the first fluid flow passage comprises a first circularopening having a diameter selected at between about 0.3 and 0.7 metresand having a centre offset a first radial distance from the axis; andthe second fluid flow passage comprises a second circular opening havinga diameter selected at between about 0.5 and 1.2 metres and having acentre offset a second radial distance from the axis, greater than thefirst distance.
 25. The apparatus as claimed in claim 21, wherein eachof the second mixing chamber and the third mixing chambers have asubstantially smooth solid sidewall.
 26. The apparatus as claimed inclaim 21, further including at least one vane member disposed in saidfirst mixing chamber, the at least one vane member configured forbreaking-up said recycled paper and cardboard as the cylinder rotatesabout the axis.
 27. The apparatus as claimed in claim 21, wherein saiddrive assembly includes a low horsepower electric motor having ahorsepower selected less than about 50 bhp.